詳細
西洋ワサビペルオキシダ-ゼは西洋ワサビ(Amoracia rusticana)の根から単離された酵素で、ペルオキシダ-ゼのフェロプロトポルフィリン類に属します。HRPは4個のジスルフィド架橋結合を有する1本のポリペプチドです。18%の糖を含む糖タンパク質です。糖の組成はガラクト-ス、アラビノ-ス、キシロ-ス、フコ-ス、マンノ-ス、マンノサミン、ガラクトサミンからなり、個々のアイソザイムによって異なります。 この酵素の分子量(約44 kDa)には、ポリペプチド鎖(33,890 Da)、ヘミン+Ca2+(約700 Da)、糖(約9,400 Da)が含まれます。HRPには少なくとも7種類のアイソザイムが存在します。 西洋ワサビペルオキシダ-ゼアイソザイムの等電点は3.0~9.0です。
アプリケーション
Horseradish peroxidase (HRP) is isolated from horseradish roots (Amoracia rusticana). It is used in biochemistry applications such as western blots, ELISA and Immunohistochemistry. Horseradish peroxidase is used to amplify a weak signal and increase detectability of a target molecule, such as a protein. Product P6140 has been used to detect low density lipoprotein (LDL).
The enzyme from Sigma has been used while assessing the skin sensitization potential of pro-haptens. It has also been used to show that peroxidase (PO) activity and its heat stability correlate with the availability of free Ca2+ ions.
生物化学的/生理学的作用
HRP readily combines with hydrogen peroxide (H2O2) and the resultant [HRP-H2O2] complex can oxidize a wide variety of hydrogen donors. The optimal pH is 6.0-6.5 and the enzyme is most stable in the pH range of 5.0-9.0. HRP can be conjugated to antibodies by several different methods that include the use of glutaraldehyde, periodate oxidation, disulfide bonds, and also via amino- and thiol-directed cross-linkers. It is smaller and more stable than the enzyme labels, β-galactosidase and alkaline phosphatase. Hence, it is the most desired label. Also, its glycosylation leads to lower non-specific binding. It is also used for the determination of glucose and peroxides in solution. Sodium azide, cyanide, L-cystine, dichromate, ethylenethiourea, hydroxylamine, sulfide, vanadate, p-aminobenzoic acid, and Cd2+, Co2+, Cu2+, Fe3+, Mn2+, Ni2+, Pb2+ ions are found to inhibit its enzyme activity.
When incubated with a substrate, horseradish peroxidase produces a coloured, fluorimetric, or luminescent derivative of the labeled molecule, allowing quantification. Horseradish peroxidase has been shown to slightly reduce the level of inhibition in a cydAB mutant.
アナリシスノート
RZ(Reinheitszahl)値は、0.5~1.0 mg/mL脱イオン水溶液で測定したA403/A275の吸光度比です。これはヘミン含量を測定するもので、酵素活性を測定するものではありません。RZ値の高い標品でも酵素活性が低いことがあります。
予備試験では、2種類の塩基性アイソザイムを含み、酸性アイソザイムは含まないことが示されています。